Step 3: Heating and bending

Step 4: Some finished shapes

These are a few bent pieces of pipe. The ends of the pipe are still taped.

PVC pipe is a great material for making things. If you ever need to bend the pipe, here's how to do it.

The trick is to fill it with sand before heating the plastic and bending it. Normally, the pipe would pinch closed in areas where it is bent, but the sand prevents that. When the heat forming is finished, you just drain out the sand.

Step 1: Safety while heating PVC

We love plastics for what they do for us, but plastic manufacture and decay tend to pollute the environment and negatively affect our health.

Vinyl Chloride, one of the components of PVC, is carcinogenic. When it is locked up in the polymer, however, it is much safer to be around. In my years of experience working with PVC, I have not noticed any adverse effects on my health from being around it.

Always work in areas with good ventilation. If you do get caught in a cloud of smoke, hold your breath and move to clean air.

When heating PVC with a gas stove or propane torch, try not to let it burn. Smoke from burning PVC is bad. With experience one burns it less and less. Don't panic the first time you do burn some. It scorches, but doesn't immediately burst into flame. Move the material away from the flame and try again. Don't breathe the smoke. Smoke avoidance comes naturally for most people.

While heating PVC over a gas flame, keep the plastic an appropriate distance from the flame to avoid scorching the surface before the inside can warm up. It takes time for heat to travel to the center of the material being heated.

Keep the plastic moving, and keep an eye on the state of the plastic. When heated, the PVC material is flexible, like leather. Beyond this stage, you risk scorching it.

A word from James, the plastic engineer -- "Just a word of warning, PVC can handle some high heats but if it catches fire, you wont be able to put it out, it does not need oxygen to burn so don't do this inside".

I do work inside, but my house is made of cement and has good ventilation. MAKE SURE THAT YOU HAVE GOOD VENTILATION. PLAY WITH FIRE -- CAREFULLY.

A few people have asked if you can do this without a stove. YES! But this might not be what you were thinking: I have done this with GREAT success using sand and a toaster oven. I put the sand on a tray in the oven and heated it to about 212˚-280˚F, then quickly and carefully (with a funnel) pour the sand into a capped piece of pvc. At this point I just held the pipe vertically with one hand (at the open end) and sort of "wiggled" it back and forth until it began acting like a cooked noodle. Pretty soon it's soft and bendy and you can do what you like with it! The sand keeps it from collapsing and provides the heat. I was consistently bending 2" radius curves with no problems!

On a different note you have a quote that says "...it does not need oxygen to burn so don't do this inside". I find that hard to believe since fire is an oxidation reaction and you can not have fire without an oxidizer (oxygen). 6th grade teaches you the three things needed for combustion: heat, fuel and oxygen. So I don't see how it could "burn" without oxygen. Am I missing something chemically here?

I'm not sure, but pvc may also give off cyanide gas when overheated. I'm sure that many plastics do give off this gas and it is a very real danger to inhale it. Any super glue that contains cyanoacrylate will certainly give off cyanide gas when burned and many plastics manufacturing processes include stuff like this in their products. PLEASE be careful when heating plastics and always have a lot of ventilation - use a fan if you have one even outside, no need to take chances with your life over a piece of plastic!

Check it out, if you are not sure, and let us know. Poly-Vinyl-Chloride doesn't sound like cyanide to me.

I agree that there are no known health benefits to breathing burning plastic. The art, not a difficult one to learn, is to not burn the plastic when you soften it. Yes, good ventilation is always important.

You would need a lot of direct heat to form toxic gas, I have bent lots of PVC with no problems at all. The bending temperature is about 100 to150°C and it takes a temperature of about 390°C or more to char PVC.

If forced to burn PVC will not produce chlorine but will emit dense acrid fumes containing noxious and toxic compounds including carbon monoxide, hydrogen chloride and possibly dioxins.However PVC will not burn on its own, it needs continuous applied heat to char it.

Well, I know how chlorine smells and I have never smelled chlorine while heat forming PVC. Of course that is below burning temperature. If you burn PVC, yes, you get some nasty fumes. The fumes don't smell like chlorine to me, but they probably contain chlorine. With fumes that smell so bad, I never hang around to analyze the aroma in detail. Anyway, and I swear I'm not lying, I'm still alive!

Your 'ible made me think. In highschool we never used heat to bend pvc pipes, for our installations we used something that you could just stick into the pipe and then bend it using your own force. Then when you were done you'd simply pull it out and the pipe would remain undamaged but bent in a nice curve. I think I have one of those things lieing in my garage. I'll check tonight and see if my memory isn't betraying me...

If it works like I remember I'll post a picture and maybe make an 'ible of my own about it.

There ya go, it was quickly found. This is what we used in school. A spring that bends the pvc pipe cold without compromising the integrity or durability of the pvc pipe also the spring is the same diameter as the innerhole so while bending the hole won't get smaller.

But it's just sticking the spring in. Look were you want to bend your pipe. And bend it with your hands until you have the shape you want. Then you just pull the spring out and your done :D It does require the use of some force but if a 14 year old can handle it I'm pretty sure everyone here can too.

Copper pipe can be bent cold using a bending spring. These are only three or four pounds each but you do need the right size for the pipe.If you had a spring the right size then you could use it with heat for bending PVC pipe.

to improve this instructable, you can also heat you PVC with a heat gun(used in art for embossing paper or other materials). Much less chance of fire, much safer, and works about as well. Good idea to post this though.

You're welcome. Apparently, a kukri is a curved knife. I don't understand the reasoning behind shaping a knife like that. If I recall correctly, boffers used to be sort of foam swords people could boff each other with, without hurting each other. If I was crossing a boffer with a kukri, I'm not sure what I would get. So how does bending PVC pipe work into making a boffer kukri?

Thanks. It seems like it could still hurt, though. I don't think the old boffers had any solid cores. They were just thicker at the handle and more flexible at the tip. Maybe there was something solid in the handle, though.